1. Field of the Invention
This invention relates generally to tools stored in an automated machining center that are selectively retrieved to machine a workpiece and more particularly to an automated machining center having an adjustable torque driving tool that is disposed to be driven at a fixed rate of speed by the automated machining center and is comprised of a clutch means to release the adjustable torque driving tool from being driven when a pre-selected torque is applied.
2. Description of the Prior Art
Automated machining centers are well-known in the art, that perform a variety of cutting functions such as milling, drilling, threading, tapping, etc. on a workpiece. These machines are normally provided with a tool carrousel that has numerous cutting tools mounted thereon for performing the variety of functions of the machine tool. The tool holder is generally a rotatable tool spindle supported in a drill head adjustably mounted on a vertical column or quill for vertical movement thereon.
The tool spindle is mounted for rotation relative to the quill and is moveable axially with respect to the drill head. Additionally, the workpiece is secured to a worktable that is moveable in an x-y horizontal plane for providing a variety of positions to perform the various cutting operations.
The machining operation is performed by the rotatable tool spindle rotatably mounted in a spindle head and arranged to be shifted vertically with respect to the workpiece. Precision cutting is performed, such that a hole center may be precisely located with respect to the axis of the rotatable tool spindle and the combined movement of the work table in its horizontal plane of movement. During the machining operation, the spindle is rotated at a pre-selected cutting speed and is fed downwardly by the drill head on the quill at a predetermined feed rate. The cutting tool is removably mounted in a chuck which is carried by the lower end of the rotatable tool spindle, and which forms a part thereof. Additionally, a tool changer is adapted to remove the used tool from the chuck at the end of a cutting operation and replace the used tool with a pre-selected new tool in an automatic manner that eliminates lost time associated with manual tool changing operations.
All of these machine functions are carried out in rapid, efficient manner in order to bring about the most efficient operation of the machine tool. The automatic control of the machine tool is provided by a numerical control system operating under the control of a punched tape or other memory device which regulates the table so as to locate a cutting center with respect to the axis of the tool, the automatic selection of the spindle speed, the spindle feed rate on the quill, and other machining functions.
For normal machining operation, it is necessary to adequately secure the workpiece to the moveable work table. This normally requires manually securing the workpiece prior to initial machining and detachment of the workpiece after machining. It would be desirable if an automated machine tool had the capability to secure the workpiece to the moveable worktable without human intervention in a continuous machining cycle and detach the workpiece from the worktable after machining.